Measuring sound by light!

Optical measurement of sound is an emerging technology for capturing airborne sound waves using light. An optical wave passing through a sound field experiences phase modulation by sound, which enables detecting sound using optical phase sensing such as interferometry and holography. The optical measurement methods bring unique and powerful features to acoustic measurement, including non-invasive remote sensing, 2D/3D visualization of the acoustic field, high spatial resolution from millimeter to micrometer scale, and direct realization of sound pressure. I am working on developing novel measurement systems and exploring attractive applications toward realizing a next-generation sound measurement paradigm.

Sound-field imaging by light: See the sound we hear

High-speed imaging of sound using parallel phase-shifting interferometry 

K. Ishikawa et al., ``High-speed imaging of sound using parallel phase-shifting interferometry,'' Optics Express, vol.24, no.12, pp.12922－12932, 2016.
[Project page] [Paper]

Deep sound-field denoiser: DNN-based noise reduction for sound-field data

K. Ishikawa et al. ``Deep sound-field denoiser: optically-measured sound-field denoising using deep neural network,'' Opt. Express, vol.31, no.20, pp.33405－20 (2023).
[Project page] [Paper] [GitHub]

Simultaneous imaging of flow and sound

★ Selected for Spotlight on Optics!
K. Ishikawa et al., ``Simultaneous imaging of flow and sound using high-speed parallel phase-shifting interferometry,'' Opt. Lett., vol.43, no.5, pp.991－994, 2018. 

[Project page]  [Paper]
 

Acousto-optic metrology: Toward the most accurate sound measurement

Midfringe locked interferometer: SOTA low-noise measurement method

★ Presented invited talk in ICA2022!
K. Ishikawa et al. ``Low-noise optical measurement of sound using midfringe locked interferometer with differential detection,'' J. Acoust. Soc. Am. vol.150, no.2, pp.1514－1523, 2021.
[Project page] [Paper]

Applications: From basic science to industry

Seeing the sound of castanets

★ Selected for Technical Area Picks!
K. Ishikawa et al.``Seeing the sound of castanets: Acoustic resonances between shells captured by high-speed optical visualization with 1-mm resolution,'' J. Acoust. Soc. Am., vol.148, no.5, pp.3171－3180, 2020.

[Project page] [Paper]

Optical measurement of nonlinear ultrasound loudspeaker

★ Selected for Editor's Picks!
K. Ishikawa et al. ``Spurious-sound-free measurement of parametric acoustic array using optical interferometry,'' JASA Express Letters vol.1, 112801 (2021).

[Project page] [Paper]